Structural basis of functional cooperation of Tim15/Zim17 with yeast mitochondrial Hsp70

Mitochondrial heat-shock protein 70 (mtHsp70) and its partner proteins drive protein import into the matrix. Tim15/Zim17/Hep1 is a mtHsp70 partner protein on the matrix side of the inner mitochondrial membrane. We determined the nuclear magnetic resonance (NMR) structure of the core domain of Tim15. On the basis of the NMR structure, we created Tim15 mutants and tested their ability to complement the functional defects of Tim15 depletion and to suppress self-aggregation of mtHsp70 in vivo. A pair of basic residues, Arg 106 and His 107, conserved Asp 111 and flexible loop 133-137, and were important (Arg 106-His 107 pair and Asp 111) or partly important (the loop 133-137) for yeast cell growth, mitochondrial protein import and the suppression of mtHsp70 aggregation. Therefore, the function of Tim15 in yeast cell growth is well correlated with its ability to suppress mtHsp70 aggregation, although it is still unknown whether inhibition of mtHsp70 aggregation is the primary function of Tim15.     

Mechanism of alcohol‐enhanced lucigenin chemiluminescence in alkaline solution

The chemiluminescence (CL) of lucigenin (Luc²⁺) can be enhanced by different alcohols in alkaline solution. The effect of different fatty alcohols on the CL of lucigenin was related to the carbon chain length and the number of hydroxyl groups. Glycerol provides the greatest enhancement. UV/Vis absorption spectra and fluorescence spectra showed that N‐methylacridone (NMA) was produced in the CL reaction in the presence of different alcohols. The peak of the CL spectrum was located at 470 nm in all cases, indicating that the luminophore was always the excited‐state NMA. The quenching of lucigenin CL by superoxide dismutase (SOD) and the electron spin resonance (ESR) results with the spin trap of 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) demonstrated that superoxide anions (O₂^?–) were generated from dissolved oxygen in the CL reaction and that glycerol and dihydroxyacetone (DHA) can promote O₂^?? production by the reduction of dissolved oxygen in alkaline solution. It was assumed that the enhancement provided by different alcohols was related to the solvent effect and reducing capacity. Glycerol and DHA can also reduce Luc²⁺ into lucigenin cation radicals (Luc^?+), which react with O₂^?? to produce CL, and glycerol can slowly transform into DHA, which is oxidized quickly in alkaline solution. Copyright © 2015 John Wiley & Sons, Ltd.     

Bacteriophage therapy against Enterobacteriaceae

Virologica Sinica - The Enterobacteriaceae are a class of gram-negative facultative anaerobic rods, which can cause a variety of diseases, such as bacteremia, septic arthritis, endocarditis,...     

Diallyl trisulfide inhibits migration,invasion and angiogenesis of human colon cancer HT‐29 cells and umbilical vein endothelial cells,and suppresses murine xenograft tumour growth

Angiogenesis inhibitors are beneficial for the prevention and treatment of angiogenesis‐dependent diseases including cancer. We examined the cytotoxic, anti‐metastatic, anti‐cancer and anti‐angiogenic effects of diallyl trisulfide (DATS). In HT29 cells, DATS inhibited migration and invasion through the inhibition of focal adhesion kinase (FAK), extracellular signal‐regulated kinase, c‐Jun N‐terminal kinase and p38 which was associated with inhibition of matrix metalloproteinases‐2, ‐7 and ‐9 and VEGF. In human umbilical vein endothelial cells (HUVEC), DATS inhibited the migration and angiogenesis through FAK, Src and Ras. DATS also inhibited the secretion of VEGF. The capillary‐like tube structure formation and migration by HUVEC was inhibited by DATS. The chicken egg chorioallantoic membrane (CAM) assay indicated that DATS treatment inhibited ex‐vivo angiogenesis. We investigated the anti‐tumour effects of DATS against human colon cancer xenografts in BALB/c^nu/nu mice and its anti‐angiogenic activity in vivo. In this in‐vivo study, DATS also inhibited the tumour growth, tumour weight and angiogenesis (decreased the levels of haemoglobin) in HT29 cells. In conclusion, the present results suggest that the inhibition of angiogenesis may be an important mechanism in colon cancer chemotherapy by DATS.     

FGF21 deletion exacerbates diabetic cardiomyopathy by aggravating cardiac lipid accumulation

Fibroblast growth factor 21 (FGF21) plays an important role in energy homoeostasis. The unaddressed question of FGF21's effect on the development and progression of diabetic cardiomyopathy (DCM) is investigated here with FGF21 knockout (FGF21KO) diabetic mice. Type 1 diabetes was induced in both FGF21KO and C57BL/6J wild‐type (WT) mice via streptozotocin. At 1, 2 and 4 months after diabetes onset, the plasma FGF21 levels were significantly decreased in WT diabetic mice compared to controls. There was no significant difference between FGF21KO and WT diabetic mice in blood glucose and triglyceride levels. FGF21KO diabetic mice showed earlier and more severe cardiac dysfunction, remodelling and oxidative stress, as well as greater increase in cardiac lipid accumulation than WT diabetic mice. Western blots showed that increased cardiac lipid accumulation was accompanied by further increases in the expression of nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) and its target protein CD36, along with decreases in the phosphorylation of AMP‐activated protein kinase and the expression of hexokinase II and peroxisome proliferator‐activated receptor gamma co‐activator 1α in the heart of FGF21KO diabetic mice compared to WT diabetic mice. Our results demonstrate that FGF21 deletion‐aggravated cardiac lipid accumulation is likely mediated by cardiac Nrf2‐driven CD36 up‐regulation, which may contribute to the increased cardiac oxidative stress and remodelling, and the eventual development of DCM. These findings suggest that FGF21 may be a therapeutic target for the treatment of DCM.     

GFAP and antibodies against NMDA receptor subunit NR2 as biomarkers for acute cerebrovascular diseases

We studied whether the serum levels of glial fibrillary acidic protein (GFAP) and of antibodies against the N‐methyl‐d ‐aspartate receptor subunit NR2 (NR2 R_NMDA) can discriminate between intracerebral haemorrhage (ICH) and ischaemic stroke (IS) in stroke patients. We prospectively recruited patients with suspected stroke (72 confirmed) and 52 healthy controls. The type of brain lesion (ICH or IS) was established using brain imaging. The levels of GFAP and of antibodies against NR2 R_NMDA were measured in blood samples obtained within 12 hrs after stroke onset and 24, 48 and 72 hrs and 1 and 2 weeks later using ELISA immunoassay. Improvement in diagnostic performance was assessed in logistic regression models designed to predict the diagnosis and the type of stroke. GFAP peaks early during haemorrhagic brain lesions (at significantly higher levels), and late in ischaemic events, whereas antibodies against NR2 R_NMDA have significantly higher levels during IS at all time‐points. Neither of the two biomarkers used on its own could sufficiently discriminate patients, but when they are used in combination they can differentiate at 12 hrs after stroke, between ischaemic and haemorrhagic stroke with a sensitivity and specificity of 94% and 91%, respectively.